In recent years, for complying with strict exhaust gas regulations applied to an internal combustion engine, it is necessary to activate an exhaust emission purifier at the time of starting up, or to maintain the exhaust emission purifier in an active state during the operation of the internal combustion engine. To this end, Patent Literature 1 has proposed an internal combustion engine in which an exhaust heating device is incorporated in an exhaust passage upstream of the exhaust emission purifier. The exhaust heating device promotes activation of the exhaust emission purifier, or maintains the active state thereof by supplying a heated gas made to generate in the exhaust gas to the exhaust emission purifier placed downstream thereof. For this purpose, the exhaust heating device is generally provided with an igniting unit such as a glow plug for generating heated gas by heating and igniting fuel, and a fuel supplying valve for injecting the fuel toward the igniting unit.